are now asking is this the summer of the shark, the great white at least. We've been tracking them up and down the coast and tonight how scientists are following them. The device they're using and how far some of the sharks, Katherine included, have gone already. Here's ABC's Matt Gutman. Reporter: It sure seems like a very sharky summer. Last week this California swimmer chopped by a great white. It's biting and you're staring at it. Reporter: The attacks no coincidence. The number of great whites up 42% since 1997. More than 2,000 of the truck-sized fish now roaming the east coast alone. The good news, we now know where a lot of them are, thanks to gps, scientists and fisherman tagging them just this weekend. Millions online tracking a 2300 pounder named Katherine. From cape cod to key west and nearly Louisiana. Their comeback, thanks to an increase in their favorite food, seelts, thanks flee not humans. I learned some sharks actually crave affection, even the hug of a reporter. David, in case you were wondering about Katherine, the great white, she's hooked a big old u-turn is heading back to south floor beaches like this one and who knows, maybe at some point this summer she could be headed to a beach near you.

This transcript has been automatically generated and may not be 100% accurate.

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